1. Field
The present disclosure relates to nanostructured light-emitting devices.
2. Description of the Related Art
Semiconductor light-emitting devices are light sources that have high efficiency and are eco-friendly. Semiconductor light-emitting devices are used in a variety of fields, such as displays, optical communication, vehicles, general illumination, and the like. The range of applications in which semiconductor light-emitting devices are used is increasing, as blue light-emitting devices and ultraviolet (UV)-ray emitting devices using nitride having excellent physical and chemical characteristics have recently emerged. The further emergence of white light or other single-color light emitting devices, which use blue light-emitting devices or UV-ray emitting devices and a fluorescent material, has also contributed to the increase in the range of applications in which semiconductor light-emitting devices are used.
The basic operating principle behind semiconductor light-emitting devices is the emission of light achieved through the combination of electrons and holes injected into an active layer. However, as a general matter, many crystal defects exist in nitride-based compound semiconductor crystals. When electrons and holes combine through the crystal defects, the semiconductor light-emitting devices emit thermal energy, instead of light energy. Reducing such non-emission re-combination is a significant factor in improving the luminous efficiency of semiconductor light-emitting devices.
The crystal defects that cause the non-emission re-combination discussed above are generated as a result of a mismatch between the lattice constants or the thermal expansion coefficients of a growth substrate and a compound semiconductor. In this regard, the present inventors have studied a technology for forming a nano-sized light-emitting structure. With respect to one-dimensional growth, nanostructures are less affected by mismatched lattice constants or differences between the thermal expansion coefficients of a growth substrate and a compound semiconductor than thin-layers. Thus, nanostructures are known to grow easily over a large area of different types of substrates.